1. Field of the Invention
The present invention relates to a portable information terminal having power supply control functions and a power supply control method therefor.
2. Description of Related Art
Portable information terminals are used in most cases while being carried around, and portable batteries are mainly used for supplying electric power to such information terminals. Therefore, in addition to improvement of the battery capacity and miniaturization of the battery size, it is also desirable to provide, for example, a function for precisely measuring the remaining battery charge and informing it to users, and a function for performing various processing in accordance with the remaining battery charge.
Recently, various portable information terminals having a plurality of functions such as a radio communication function (for example, the same function as a portable telephone or a PHS (Personal Handyphone System)), an information processing function, and an image pick-up function such as those of digital cameras, are developed. Hereafter, such portable information terminals will obtain more complicated and advanced functions.
In a portable information terminal having several functions, since electric power consumption of each of circuits for performing respective functions are different from each other, it is difficult for users to predict the remaining battery life only based on the remaining battery charge. For example, although a function as a PDA (Personal Digital Assistant) can be activated for about several months by only one battery charging or battery exchange, a function as a portable telephone needs a battery charging once a week. Therefore, in a portable information terminal having both the functions, the operating time of the PDA function will be greatly shortened by the operation of the portable telephone function, and it is difficult for users to predict the remaining battery life.
The present invention is made in order to overcome the above drawbacks of the prior art, and the object of the present invention is to provide a portable information terminal which can restrict each function according to the remaining battery charge, and to provide a power supply control method therefor.
In order to achieve the above object, a portable information terminal of the present invention comprises a plurality of function processing units which respectively perform various functions; a battery which supplies electric power to the function processing units; a remaining battery charge detecting unit which detects remaining battery charge of the battery; and a power supply control unit which compares the remaining battery charge with each of power supply limiting values determined in advance with respect to the function processing units, and, when the remaining battery charge becomes lower than at least one of the power supply limiting values of the function processing units, stops power supply to the at least one of the function processing units and/or outputs warning signals.
According to the portable information terminal of the present invention, the operation of each of the function processing units such as a radio communication terminal unit, a data processing terminal unit, a digital camera unit, etc., is individually stopped, and/or warning signals are output, by comparing the present remaining battery charge with the power supply limiting values determined in advance with respect to each function processing unit. Therefore, it is possible to prevent the operating time of one function processing unit from being greatly shortened by the use of another function processing unit, and users can predict the remaining battery life for each of the function processing units.
The portable information terminal according to another aspect of the present invention comprises a plurality of function processing units which respectively perform various functions; a battery which supplies electric power to the function processing units; a CPU which controls the function processing units; a remaining battery charge detecting unit which detects remaining battery charge of the battery; and a processing control unit which compares the remaining battery charge with each of power supply limiting values determined in advance with respect to the function processing units, and, when the remaining battery charge becomes lower than at least one of the power supply limiting values of the function processing units, controls the CPU so that the CPU restricts the operation of the at least one of the function processing units.
In this case, when the present remaining battery charge value becomes smaller than the power supply limiting value of one function processing unit, the processing control unit instructs the CPU to perform the restriction of the one function processing unit. Thus, the electric power consumption for performing the one function processing unit can be decreased as well as the case where the power supply to the function processing unit is limited, and the processing control unit can function as well as the power supply control unit in the first aspect. The xe2x80x9crestrictionxe2x80x9d may include completely stopping the function processing unit and partially stopping the function processing unit while maintaining the minimum functions of the function processing unit.
The power supply control method of the present invention is a method for controlling power supply to a portable information terminal having function processing units which respectively perform a plurality of functions, and the method comprises detecting a remaining battery charge of a battery which supplies electric power to the function processing units which respectively perform the functions; comparing the remaining battery charge with each of power supply limiting values determined in advance with respect to the function processing units; and when the remaining battery charge becomes lower than at least one of the power supply limiting values of the function processing units, stopping power supply to the at least one of the function processing units and/or outputting warning signals.
According to this method, the operation of each of the function processing units such as a radio communication terminal unit, a data processing terminal unit, a digital camera unit, etc., is individually stopped, and/or warning signals are output, by comparing the present remaining battery charge with the power supply limiting values determined in advance with respect to each function processing unit. Therefore, it is possible to prevent the operating time of one function processing unit from being greatly shortened by the use of another function processing unit, and users can predict the remaining battery life for each of the function processing units.
The power supply method according to another aspect of the present invention comprises detecting a remaining battery charge of a battery which supplies electric power to the function processing units; comparing the remaining battery charge with each of power supply limiting values determined in advance with respect to the function processing units; and when the remaining battery charge becomes lower than at least one of the power supply limiting values of the function processing units, controlling a CPU, which controls the function processing units, so as to restrict the operation of the at least one of the function processing units.
In this case, when the present remaining battery charge value becomes smaller than the power supply limiting value of one function processing unit, the processing control unit instructs the CPU to perform the restriction of the one function processing unit. Thus, the electric power consumption for performing the one function processing unit can be decreased as well as the case where the power supply to the function processing unit is limited, and the processing control unit can function as well as the power supply control unit in the previous aspect.